Dynamometer



2 Sheets-Sheet 1.

(No Modell) H. C. SPAULDI-NG.

DYNAMOMBTBR. No. 414,598. Patented Nov. 5, 1889.

sNvEN-VUR f Mp, -onmclmmm (No Model.) 2 sheets-sheen 2. H. C. SPAULDING. DYNAMOMETBR.

No. 414,598. 888811888 Nov. 5, 1888.

WITNEIEJEE y INVENTFQ.

LA, M8888. @mamy HOLLON C. SPAULDING, OF

PATENT BOSTON, MASSACHUSETTS.

DYNANIOMETER.

SPECIFICATION forming part of Letters Patent No. 414,598, dated November 5, 1889,

Serial No. 307,433. (No model.)

To all whom it may concern:

Be it known that I, HOLLON O. SPAU LDIN G, a citizen of the United States, residing at B oston, in the county of Suffolk and State of Massachusetts, have invented certain new and useif u1 Improvements in Dynamometers 5 and I do hereby declare the tollowingvto be a full, clear, and exact descript-ion of the invention, such as will enable others skilled inthe art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this speeication.

My invention has for its object the production of a dynamometer or tension-measuring machine adapt-ed to be readily applied and used for determining the power transmitted to any driven machinery.

To that end my invention consists, essentially, of a pair of interposed pulleys which, by means of belts, receive the power from the main driving-l'iulley and transmit it to the pulley forming a part of the machine to be driven. One of the said interposed pulleys is loosely mounted upon a shaft and is oonnected with a strong` coiled spring, the other end of the spring being secured to the pulleyshaft. To the latter is secured a slotted disk, back of which is loosely mounted a colored cam-disk arranged to travel in unison with the pulley, all as will be more fully hereinafter set forth and claimed.

By means of my improved dynamometer it is possible to take a reading of the instrument at any time while in operation and while revolving' at any velocity within its limits. The tension or pull7 upon the belt at any instant is indicated by the relation of the slot of the disk to the uncovered periphery of the cam at the same time, the operator simply having to take the distance in a pair of dividers or other analogous means lying between the center of ,the shaft and the exposed point in the cams surface. This distance or read-ing (which indicates the torsional strain to which the spring is subjected at the time) is next referable to a scale previously graduated to the spring used, such scale usually indicating pounds. Now by knowing the velocity of the belt at the time oi' taking the record it is easy to determine the horse-power. Practically, however, certain coefficients or factors are employed, which serve to greatly lessen the labor of computations.

In a class of dynamoniet-ers heretofore in use, which depend uponacolumn of confined iiuid to indicate the variations in pressure, it is practically impossible to obtain suiliciently accurate scale-readings under all conditions, owing to changes or fluctuations due to leakage of the fluid, thereby rendering such instruments inaccurate and unreliable.

In the appended two sheets of drawings illustrating my invention, Figure l, Sheet 1, is a horizontal sectional view oi the device as a whole. Fig. l is a similar view showing a modified form of the loose pulley, dac. Fig. 2 is a side view with some of the parts removed. Fig. 3, Sheet 2, is a front view of the slotted disk adapted to be secured to the pulley-shaft. Fig. et is a front view of the cam-disk loosely mounted upon the pulley-shaft and adapted to revolve in complete unison with the pulley. Fig. 5 shows in reduced scale a pulley or machine driven from the main-line shaft. Fig. 6 is a similar view, the driving belt being removed, and showing the manner of applying and' connecting my improved dynamometer as in use. Fig. 7 is a front view, in reduced scale, of the cam-disk having a double cam painted or otherwise indicated thereon; and Figs. 8 and 9 represent modified forms of the disk shown in Fig. 3.

Amore detailed description of my improved dynamometer, including the manner of its operation, is as follows:

Referring again to the drawings, A indicates the apparatus as a whole.

a, c, designate the two side frames arranged to carry ,the several parts of the mechanism. The sides are connected transversely by collared tie rods t', provided with end nuts adapted to be screwed firmly against the faces of the frame. Y

b and h indicate two short pulley-shafts mounted to revolve in the frame a. To the first-named shaft h is secured a pulley c, from which, by means-of a belt s2, the power is transmitted to the pulley I3, which in turn drives any suitable machine, G. i Upon the other short shaft b a pulley d is loosely mounted, which may be driven by a belt s',

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leading from a driving-pulley p, secured -to the .main-line shaft S, Fig. 6. The pulleycl, as drawn, is hollow, and is provided with a hub portion at each end, as shown in Fig. l. Intermediate of said hubs and surrounding the shaft b is located a coiled spring e, having one end e secured to the pulley and the other end c2 secured to the shaft b. The power of the pulley c is transmitted to the pulley d by the gears g, or vice versa, as desired. The intermediate gear g. obviously causes the two pulleys c d to revolve in one direction, thereby obviatin g the employmentv of a crossed belt.

To one side of the hub of the loose pulley is secured a small gear 7i, which intergears `with agear 7i, of the same size, secured to a plished by omitting the gears and forming a sleeve -upon the corresponding end, the

-sleeve extending through the frame-bearing :and having the cam-disk m secured-to its router end, as indicated lbyl Fig. 17E-g but such van arrangement materially increases the percent-age of friction.

'-shaped igure formed on itsfsurface. 35:

-The disk m (seeFig. 4) has a spiral or cam- The proper form maybe best determined by making an actual test of the spring torsionally, the longest radius, terminating at u2, indicat- -.ing the greatest pressure, and the shortest radius,measured from the center to the point it', belng the line of no pressure or zero. I would state that practically I prefer to use a The disk, as drawn shaft b', and is adapted to revolve in exact unison with the pulley d by means of screws or pins passing through holes m3, formed in the disk and tapped into the contiguous looselymounted gear h.

In some cases I may yprovide the disk m :with two oppositely-arranged cams m4 m5, .having dissimilar colors, -as indicated byl Fig. 7. By reason of the employment of a double cam thev readings may be takenwith .greater exactness as compared with the. sin-j gie-cam disk of equal diameter, from the fact that lfor equal angular distances the net radius or offset of vthe latter will be but one- @half that of the former. Immediately in front of the cam-disk is located a thin cover or exl.posing-disk o, (see Fig. 3,) whichis rigidly secu-red to the shaft b. This disk is cut away at.. one side, asv at 02, one or both sides of the opening forming radial lines 219, the .same

' bration.

being so arranged with relation to 'the camdisk that the inner end its of the radial Side practically coincides withA the zero-point u of the cam-disk when the pulle;7 d is in al state of rest and indicating no tension or pressure upon the belt. In Fig. S the cover o has the form of 'a half-disk, which is more particularly adapted to be used in 'combination with the double cam shown in Fig. 7. l

In order to cover or protect the outer ends u of the sides t2, the rim or periphery of the diskmay be continued, as shown in Fig. 9. The'face of the covers o may be painted or polished, as desired.

The pperation maybe described as follows: Assuming that a machine having a drivingpulleyB is to be tested to ascertain the power required to operate it,I iirst remove thedriving-belt k, Fig. 5, and substitute my'dynamometer A, the latter being connected with the main pulleys p B by the two short belts s s2, which respectively engage the dynamometer-pulleys d c. The two side frames a are secured together by braces i', to one of which a stay t may be attached, the same extending to the floor,where it is secured,vas at t', Fig. 6. By .this arrangement the stay serves to maintain the dynamometer in posi.

tion when in use and also prevents lateral vi- Now upon running the driving-belt s', Fig. 6, in the arrow direction the pulley d will be revolved in the same direction against the tension of the spring e, thereby revolving the shaft b. The power is transmitted therefrom to the driving-pulley B of the machine vto betested Vby means of the gear-train g,

pulley c, and belt s2. The pulley B. maybe a clutch-pulley or otherwise adapted to-be used for readily throwing the load on orl off the machine, the parts now'being out-of clutch. Thus far the only power developed is that required toovercome the friction of the Vmoving parts. At the same time the inner point u of the cam m coincides very nearly with the inner end a3 of the radial Side 752 of the disk or cover 0, substantially as shown in Fig. 2. Now'upon clutching the pulley B or otherwise throwing the load or work of the machine upon the belt s2 it will be found that the strain upon the belt will cause the cover o to change `its angular position with relation to the cam m. 4As soon as the cam and cover become .steadyj both nowrevolving practically in unison, the attendant, in order to take the reading or indication, next places, say, the point of one leg of 4a pair of dividers in the center of the Shaftv at the same-time opening them, andl causes the point of the ,other legto extend-along they working edge or radial side t2 ofthe cover-opening o2 .to the limit of color Edisclosed or exposed of the cams outline. lThe distance thus found minus the distancefrom the center of the shaft to the inner end .u of ,the cam is now transferred to a suitablygraduated scale to indicate the torsionof lthe spring e in pounds, thereby determining the IOO lIO

gross stress or tension upon the belt, which pressure multiplied by the velocity of thel belt in feet per minute obviously gives the foot-pounds, which maybe readily reduced to horse-power by dividing the product by thirty-three thousand.

In case the double-cam disk, Fig. 7, be used the manner of ascertaining the dist-ance to be transferred to the scale is substantially the same as just described, except that the latter scale for equal lengths will indicate only about one-half the pressure of the former'or singlecam arrangement. Consequently the errors in reading will be relatively reduced. This result may be stated as follows, assuming that one cam fm, 7 of the disk m be yellow and the other m5 black, and that the cover o, Fig. S, be mounted in front; Now when any portion of the yellow cam is visible (revolving, as indicated) the distance taken in the dividers will equal that measured from the center to the point at which the working side t2 of the cover o intercepts said color up to one-half a revolution of the cam or its radius, after which, as the black canine5 becomes exposed, the distance taken will al- I always equal said radius plus the length from the center tothe interception of the cam by the working-edge t2.

The relation of the cani and cover may be transposed that is, the cover o may 'be mounted intermediate of the cam and gear h-and said cover and cam (one or both) may be made of glass or other suitable transparent material, if desired.

- The relation of the dynarnometer to the machine-pulley B, as represented in Fig. 6, may

be reversed by inverting the dynamometer, in

which case the pulley d would receive the belt s2 and operate the pulley B.

In the event of a crossed belt being used,

as indicated by dotted lines in Fig. the dy namometer need have but two intergearing gears g of larger diameter, the intermediate gear being omitted.

I would state that the ofice of the stayt (or stays, as two or more may be employed) is not solely to keep the dynamometer in position when in use, but it also serves to take up the slack of the belts by simply carrying `to revolve in exact unison with the pulley,

and an outer or cam-exposing disk secured to the shaft, all constructed, arranged, and adapted for opera-tion, whereby any change or variation of the pressure in working produces a relative angular change in the position of the two disks, substantially as hereinbefore set forth.

4. In a dynamometer, the combination of a driven shaft, a pulley (Z, mounted thereon, a spring connecting said shaft and pulley, a

.belt connected with the pulley, and a tension-indicating apparatus, substantially as hereinbefore described, whereby any change or varia-tion in the tension of the belt produces a change in the relative angular positions of the said pulley and shaft, substantially as hereinbefore set forth.

5. In a dynan1o1neter,the combina-tion of a driven shaft, a pulley mounted thereon, a spring connecting said shaft and pulley, a colored earn-disk revolving in unison with the pulley, and a cam-exposing disk o, secured to said shaft, combined and arranged, whereby any change er variation in the tension of the belt produces a change in the relative angular positions of the two disks, substantially as hereinbefore setforth.

6. The combination, with driver and driven pulleys, of the interposed dynamometer A, hereinbefore described, consisting of the frame a, shafts l) b', mounted to revolve therein, a pulley c, secured to the shaft b, a pulley d, loosely mounted upon the shaft h', a spring e, connected Withthe pulley d and its shaft, a colored cani-disk m, arranged to travel in unison with the pulley d, a cam-exposing disk o, secured to the shaft 1) in front of said disk m, and a stay t, adapted to maintain the apparatus in position when in use, substantially as shown and hereinbefore set forth.

Intestimony whereof I have affixed my signature in presence of two witnesses.

IIOLLON C. SPAULDING.

Witnesses:

CnAnLns HANNIGAN, Gno. H. REMINGTON.

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